<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>灯泡开关 switch02</title>
		<style type="text/css">
			#box{
				text-align: center;
			}
			#btn{
				margin: 0 auto;
				width: 50px;
				height: 50px;
				line-height: 50px;
				color: #fff;
				background-color: #ddd;
				border-radius: 100%;
				cursor: pointer;
			}
		</style>
	</head>
	<body>
		<div id="box">
			<div id="btn">
				开
			</div>
			<img id="img" src="img/pic_bulboff.gif" />
		</div>
		
		<script type="text/javascript">
			var btn = document.querySelector('#btn');
			var img = document.querySelector('#img');
			btn.onclick = function(){
				if(this.innerHTML == '开'){
					img.src = 'img/pic_bulbon.gif';
					this.innerHTML = '关';
					this.style.backgroundColor = 'green';
				}else{
					img.src = 'img/pic_bulboff.gif';
					this.innerHTML = '开';
					this.style.backgroundColor = '#ddd';
				}
			}
		</script>
	</body>
</html>
